Interleaved practice improves delayed posttest performance compared with blocked practice¶

Claim · All claims
Evidence · 1 study · causal r? · q3 · i2 medium
Currency · newest study 2026 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i2 Interleaved practice led to less time and fewer trials needed in the posttest than blocked practice. → Ines Zeitlhofer 2026

Evidence¶

Ines Zeitlhofer 2026¶

Ines Zeitlhofer, Joerg Zumbach. (2026). Germane processes moderate the effectiveness of complex desirable difficulty tasks. Instructional Science. https://doi.org/10.1007/s11251-026-09807-1

q3 · i2 · causal · r?

The same MANOVA on posttest time and trials showed a main effect of desirable difficulty (η² = 0.09): "interleaved practice leads to less time" and fewer trials than blocked practice in the delayed posttest.

"Multivariate results also show a main effect for desirable difficulty (F (2, 127) = 6.52, p = .002; η² = 0.09; Hypothesis 1.2) revealing that interleaved practice leads to less time ( F (1, 128) = 12.64, p < .001, η² = 0.09) and trials needed in the posttest"

Discussion¶

Related Claims¶

• The interleaving benefit is not caused by spacing, and the benefit extends to delayed tests — a broader claim this one bears on
• At a 1-day test delay, interleaved practice yields a moderate benefit over blocked practice (d = 0.42) — a narrower finding that bears on this claim
• Interleaved practice produces higher mathematics test scores than blocked practice in a classroom experiment — a narrower finding that bears on this claim
• Interleaved practice provided near immunity against forgetting over a 30-fold increase in test delay — related
• Interleaving category examples improves inductive category learning for visual and mathematical materials, but not for expository texts or word categories — related
• Retrieval practice and spaced retrieval improve achievement and retention by medium amounts, while interleaving helps category learning only for some materials and blocking beats it for words — related
• Alternating example-practice pairs produce faster and more accurate near-transfer solutions than blocked presentation of examples followed by practice — related
• The interaction of complexity and desirable difficulty does not significantly affect posttest performance — related
• Interleaved practice yields lasting learning effects at delayed posttests in spelling and second-language grammar — a narrower finding that bears on this claim